Hydraulic ram construction



Feb. 11, 1941. E, M, PIL-AUSER 2,231,680

HYDRAULIC RAM CONSTRUCTION Filed May 16, 1957|||||||||||v||1||||||||||||||||u||||| Of n Patented Feb. 11, v1941PATENT OFFICE 2,231,680 HYDRAULIC RAM CONSTRUCTION Edward M. Pfauser,Elm Grove,. Wis., assignor to Blackhawk Mfg. Co., Milwaukee, Wis., a.corporation of Wisconsin Application May 10, 1937, Serial No. 141,748

' 6 Claims.

This invention relates to hydraulic ram units, and more particularly isdirected to units of this type used for pushing and pulling operationsin connection with lifting, bending and straightening of metalstructures and the like.

In ram units of this type, which are operable in all angular positions,the fluid for actuating the plunger is transmitted to the ram unit fromva remote pressure developing source through a flexible pressuretransmitting line. When the pressure is re1eased,'it is ordinarilynecessary to drive the. uid from the ram unit by pushing the plungerinward. to bring it to its retracted or initial position. It isfrequently inconvenient to do so.

The present invention contemplates overcoming this disadvantage byincorporating suitable means in the ram unit for automatically restoringthe ram plunger to its` inner limiting position with the cylinder uponrelease of' the fluid pressure. This vmechanism operates entirelyindependently of the operator, and is controlled solely by the releaseof pressure at the pump or pressure developing source;

Another feature of the present invention is the provision of. a novel.type of sealing means between the -plunger and the cylinder, consistingof annular V-shaped cups secured to the inner end of the ram plungerand'eifectively sealing the space between the cylinder and plunger toprevent leakage of fluid therepast.

One of the important advantages obtained by the present constructionresides in the provision of a one-piece ram cylinder constructionconsisting of the base, cylinder portion and top cap. all formed from asingle piece of stock, such as cold rolled steelshafting or the like.This eliminates any possibility of leakage at threaded junctions, suchas heretofore employed and produces a more. compact and stronger unit.In combination with the plunger construction, a very strong, highlyeiicient and compact unit is provided which is light in weight therebyto facilitate its positioning in any location desired.

Still another feature of the present invention is the provision of stopmeans carried by the outer end of the ram cylinder and cooperating withcorresponding means on the inner end of the plunger for limiting outwardmovement of the plunger. Preferably I form such means withfrusto-conical contact surfaces which move into abutting engagement uponextension of the plunger. This effectively prevents any `cold flowing ofmetal at the stop surfaces, thusv elimmating the burring produced by thesquare shoulder abutments hereto employed, which tended to cause bindingof the stop disc of the plunger after continued use.

In connection with the automatic plunger. return means, I preferablyprovide a novelv type of pre-stressing means which initially tends tohold the `plunger in its inner limiting position, and is positive in`returning the plunger to such klimiting position. The construction issuchv that easy assembly and adjustment of such prestressing means ispossible.

The present construction is also advantageous in the economy andsimplicity of construction and compactness of the parts, therebyfacilitating assembly and use of the mechanism.

Other objects and advantages of the present inventiony will appear morefully from the following detailed description Which, taken inconjunction-with the accompanying drawing, will .disclose to thoseskilled in the art the particular construction and operation of apreferred form of the present invention. t

In the drawing:

Figure 1 is a vertical sectional view through a ram unit embodying thepresent invention;

Figure 2 is an enlarged view of a portiony of the structure shown inFigure 1, withy portions.

broken away for the sake of clarity. l

Referring now in more -detail to the drawing, the ram cylinder isindicated generally at Iv and comprises a base 6, a cylindrical bodyportion 1 and an end portion 8. This member is preferably ,formed fromcold rolled steel shafting as a one-,piece unit, whereby leakage atthreaded connections, which was possible in prior ram cylinderconstructions in which the base member was threaded to a rolled o-rseamless tubular cylinder, is eliminated.

The lower end of the base member is recessed' as indicated at 9, and isprovided with suitable internal threads or similar coupling meansadapted to form quick detachable couplings for securing various work andreaction engaging members to the end of the ram cylinder for use invarious metal bending and straightening operations. The type of membersadapted to be connected in this manner is more clearly disclosed in mycopending application, Serial No. 72,750, filed April 4, 1936,'nowPatent No. 2,165,504.

As the upper end 8 of the ram cylinder Ipro' vide an internal threadedportion I0 adapted to receive the stop ring l2` which is threadedtherein, and' which preferably is formed with a tapered or frustoconical stop surface, for a purpose to be hereinafter described. Theouter surface of the end portion 8 may also be threaded for receivingvarious types of coupling members, as disclosed in my patent referred toabove. and when such couplings are not employed, the threads may besuitably protected by the sleeve ring I4 threaded thereover andenclosing this portion of the ram cylinder.

The ram plunger is indicated generally at I5. and comprises a tubularmember having reduced endportions I6 and I1, which lform radialshoulders I8 and I9, respectively. At its outer end I6 the plunger isprovided with a suitable coupling engaging member 28 which may besecured thereto by means of a pin 22 or in any other suitable manner.'I'he member 28 may be externally threaded as indicated at 23 forreceiving quick detachable work-engaging members or the like of the typeshown in my aforesaid copending applications. Obviously, other types ofcoupling means may be employed in place of the threads 23, such as asnap-on plunger type of coupling, as described in Mandi & Pfauser PatentNo. 1,982,008, issued November 27, 1934.

Seated against the shoulder I9 at the inner end of the plunger ls .thestop disc 24 which is provided with a corresponding bevelled shoulder 25adapted to engage the surface I3 of the stop ring I2 when the plungermoves into its outer limiting position. The provision of the conicalsurfaces for stopping the outward movement of the plunger insures that apositive stop will be obtained without any cold owing of metal due topressure, which thereby eliminates the burring produced by the shouldertype of abutments which have heretofore beenV employed. Such burringtends to cause binding of the stop disc of the plunger after continueduse, scoring the surface of the plunger, and producing faulty operationof the unit. The angle of the shoulder 25 is obtuse enough that there isno -tendency of the parts to stick by wedging together. 'I'he upwardthrust thereby does not batter the stop ring I2 inwardly, as in priorconstructions; but instead tends to spread the same radially. The inneraxially facing portion of the stop disc 24 is provided with an annulargroove of substantially V-shaped section, which is adapted to receivethe plunger cup 26 also of annular V-shape. An intermediate plunger cup21 is provided between the cup 28 and the outer cup 28. 'I'hese cups arepreferably formed of leather or similar material forming an effectiveseal with the internal surfaces of the body portion 1 of the plunger,and are maintained in tight engagement with the external surfaces of thereduced end I1 of the plunger and the internal surface of the cylinder 1by means of a spreader ring 29 which has an annular bevelled projectingshoulder engaging the outer cup member 28, and held in position by meansof the retaining nut 38 threaded inwardly over the end I1 of the plungerto force the spreader member 29 axially against the plunger cups. Thepacking ring or cup 21 or 28 may be made of a material impervious to theoil or other liquid used in the ram, as and for' the purpose disclosedin my copending application Serial No. 68,244, of March 11, 1936, toprevent seepage of the liquid at high pressure through the porousleather cups 26 and 21 or 28, as the case may be.

Preferably a suitable spring washer 32 is disposed intermediate thespreader 28 and the retaining nut 30. The washer 32 is preferably formedof wavy contour to be flattened as the nut 38 is drawn up. The nut 30 isprovided with a suitable kerfed portion 33 facilitating its threadingover the inner end of the plunger. This provides an effective seal toprevent any leakage of iluid under pressure from the interior of thecylinder outwardly past the plunger cups 26, 21 and 28. This alsoinsures that the fluid will eil'ect positive displacement of the plungeroutwardly of the ram cylinder. l

It is tobe noted that when the ring 24 strikes the stop ring I2 the fullhydraulic pressure on the piston tends to compress the packing cups 26,21, 28 between the back of ring 24 and the front of ring 29. When arubber cup is employed for the cup 28, it will iiow into the availablespace and distribute the applied pressure, preventing cutting of theleather cups even though the angle of the backing ring 29 is not thesame as the angle of the cups 26, 21. The same is true if theintermediate cup 21 is made of rubber, and cups 26 and 28 material. v

The plunger is preferably provided with an axial recess 35 extendingfrom the inner end I1 thereof to approximately the plane of the radialshoulder I8. Within this recess I dispose a helically coiled springmember 36, which is preferably of rectangular or ovate section, and isclosely wound, being provided at its lower end with the normallyextending portion 38 adapted to lit around the shank of a retaining stud39 which threads into the plunger base 6 and is accessible from theinlet opening 40 to which the flexible fluid transmitting conduit isattached when the unit is placed in operation. This conduit (not shown)is connected to any desired pressure developing means, as disclosed inmy patent aforesaid.

'I'he fitting (not shown) which is inserted in the opening 48 comprisesan' outer part with a tapered thread for making a fluid tight lit withthe threads at the inner end of the opening 40 and a cylindrical partback of the threads which cylin-A drical part fits closely the outercylindrical part of the opening 40 so that side strain on the fittingwill not tend to cause loosening of the threaded point.

The opening 40 is formed in the portion of the body below .the shoulder49, whereby the threaded socket may be formed in the solid part of thecylindrical body of which the ram cylinder is constructed anddisposed`within the confines of the cylindrical body.

At its upper end, the spring member 36 is provided with several coils 42of smaller diameter than the normal spring diameter which engage over asuitable retaining beading member 43 carried by the ball members 44 uponthe head end 45 of an adjusting screw 46. d

'I'he outer reduced end I6 of the plunger is provided with a suitablethreaded portion 41, and at its outer end is counter-bored and tapped asindicated at 48. In assembling the mechanism, the coils 42 of .thespring are rst engaged over the retainer 43 which is mounted by means ofthe balls 44 on the head 45 and preferably has its outer end crimpedover, as indicated at 49 to retain the member on the head 45. The nut 50is then threaded down over the stem of the screw 48 to lock the coils 42of the spring about the shank of the screw 46, and the ball supportedretainer 43 permits relative movement of the spring members, providing aswivel bearing at this point which allows swivelling bf the ram ofleather or other pervious plunger with respect to the spring memberWith#- \7 out putting any undue torsional strain on the spring. Thesmaller coils actas a ledge or abutment on which the ball retainer 4ltakes the load of the spring while the nut 50 holds the ball retainingunit and'screw in position on the spring until the threaded end of thescrew can be threaded into the opening 41 by means of a screw driveroperated from the opposite end of .the spring. After the spring andscrew have thus been initially secured to the outer end of the plunger,the plunger is inserted into the ram cylinder and the stop disc I2 isthreaded into the end 8 of the cylinder to provide a bearing guide forthe plunger and also to serve as a stop member, as heretofore described.The lower end of the spring is then secured by means of the screw 39 tothe base portion of the cylinder.

This initial setup does not provide for any stressing ofthe spring, andin order to insure that the plunger will positively return to` itsinitial limiting position upon release of thepressure in the cylinder, Iprovide suitable mechanism at the outer end of the plunger for insuringa predetermined prestressing of the spring member.

It will be noted that the outer end of the screw 46 is provided with akerf 52, which may be engaged by a screw driver passed down through theopening 41 'to thread the screw 43 outwardly of the end I6 of theplunger, thereby placing tension upon the spring member to produceinitial prestressing thereof, which will insure that the plunger returnsto its innermost limiting position upon release of pressure. the screw46 against relative movement which might tend to unthread the same fromthe plunger, I provide a lock screw 53 which is threaded into the outerend of the plunger and jams against the end of the screw 46 to lock thesame in position.

In order to prevent leakage of theffluid within the recess 35 of theplunger outwardly through the threaded opening 41, a suitable plungerplug 54 may be provided, which is threaded into =the counterboredportion 48 and seats against the shoulder 55 to provide a fluid-tightseal which will preventv any leakage of pressure internally through theplunger.

It should be noted that the spreader member 29 incorporated in thesealing assembly at the inner end of the plunger has an annular bevelledshoulder portion with' a wider tapered surface than that of the plungercups 26 to 28. whereby upon pressure engagement of the spreader with theplunger cups, there is a tendency to move the outer edge portions orlips of the cups outwardly, causing them to contact the plungerand-cylinder surface. vAt the same time' the follower or spreader, whenmoved into contact with the center of the V-cups, causes them to expandunder pressure. Th'is produces a more efficient sealing action than washeretofore possible, and prevents leakage of fluid past the stop disc.24.

The threaded portion about the external surface of the end 8 of thecylinder is shown only as one example of a suitable way to attachfittings or work reaction members. Other mechanical expediente formingquick detachable couplings may be employed without departing from thepresent invention. V

The spring 36 makes it ypossible to obtain many of the effects of thepush-pull type of ram, and has s'ome advantages over such a ram, sinceas soon as the valve controlling the fluid pressure to the ram unit isopened, the spring immediately retracts the plunger, whereas, withthepush-pull In order to maintain plunger is moved outwardly of thecylinder thereby to gauge the extent of movement imparted to the work bythe ram.

It will be readily understood that by reason of the onepiececonstruction of the ram cylinder, simplicityv of design is obtained withthe additional elimination of possible leakage at the Vthreadedconnections ofthe parts which are ordinarily used in making up such acylinder. Further, the one-piece construction produces a simp lifledplunger guide and stop ring mechanism at the outer end of the cylinder,and also provides -ready means for the attachment and detachment ofwork-engaging members.

I am aware that various changes and modifications may be made in certaindetails of the construction herein "shown and described, and I thereforedo not intend to be limited except as defined by the scope and spirit ofthe appended claims.

I claim:

1. A ramunit comprising a ram cylinder, a ram plunger reciprocatorytherein, a coiled spring within said plunger, anti-friction meansproviding a swivel support for one end of said spring within the outerend of said plunger, means for securing the other end of said spring tosaid cylinder adjacent the inner end of said plunger, and means at saidouterv4 end of said plunger for producing a predetermined stress in saidspring reduced end portion, a load supporting screwk having clampingmeans receiving said end portion for supporting the same from the outerend of said plunger, means for securing the other `enel of said springmeans to the base of said cylinder, locking means for locking said loadsupporting means in predetermined position in said plunger, sealingmeans preventing internal or external leakage of uid past said plunger,and means operable from the outer end of said plunger for producing apredetermined tension in said spring means after said plunger has beenassembled in said cylinder.

3. A ram comprising a ram cylinder having a closed end, a plungerinserted into the. opposite end of' said cylinder and supported forreciprocatory movement therein, an axial bore within said plunger forreceiving a coiled spring member. means at the outer end of said plungerproviding an anti-friction load supporting bearing for one end of saidspring member, means accessible externally of said cylinder for securingthe opposite end' of said spring to the closed end of said cylinder, andmeans in the outer end of said plunger for producing predeterminedinitial stress in said spring member after said plunger has beenassembled in position.

4. A ram unit comprising, in combination, a ram cylinder closed at oneend and open at the other. a ram plunger mounted for movement out of andinto said cylinder through said open end, said ram plungerbeingl-tubular in form and closed at the outer end and open at the innerend, a coiled spring within said ram plunger, means for fastening oneend of said spring to said ram cylinder adjacent the closedend thereof,and means for fastening the other end of said spring to said ram plungeradjacent the closed end thereof, the last named fastening means beingadjustable through said closed end of said ram plunger for tensioningsaid spring after assembly of said Aram plunger and spring with saidramcylinder.

5. A ram unit comprising, in combination, a. ram cylinder open at oneend and closed at the other and having a transverse port adjacent saidclosed end opening into said cylinder, a ram plunger mounted formovement out of and into said cylinder through said open end, said ramplunger being tubular in form and closed at the outer end and open atthe inner end, a coiled spring Within said ram plunger, a retainingmember insertable through said transverse port and fastened to the wallof said ram cylinder for securing one .end of said spring thereat, andmeans for fastening the other end of said spring to said ram plungeradjacent the closed end therecLthe last named fastening means beingadjustable through said closed end of said ram plunger for tensioningsaid spring after assembly of said ram plunger and spring with said ramcylinder.

6. A ram unit comprising, in combination, a ram cylinder closed at oneend and open at the other, a ram plunger mounted for movement out of andinto said cylinder through said open end, said ram plunger being tubularin form and closed at the outer end and open at the inner end, a coiledspring within said ram plunger, means for fastening one end of. saidspring to said ram cylinder adjacent the closed end thereof, and meansfor fastening the other end of said springto said ram plunger adjacentthe closed end thereof including a member axially threaded in saidclosed end of said ram plunger and adjustable therethrough fortensioning said spring after assembly of said ram plunger and springwith said ram cylinder, and locking means for holding said threadedmember in any operative position to which it may be adjusted to preventSpring.

EDWARD PFAUSER.

